1. Field of the Invention
The present invention relates to an interface apparatus of the type used, for example, to couple an end of a waveguide and an electromagnetically shielded housing, such as an end of an optical fibre and a subassembly of an optoelectronic module. The present invention also relates to a connector apparatus of the type, for example, for carrying an end of a waveguide, for example an optical fibre, for coupling to an electromagnetically shielded housing, such as an optoelectronic module. The present invention also relates to a method of reducing electromagnetic radiation leakage from a coupling between a connector for carrying an end portion of a waveguide, such as an optical fibre, and an electromagnetically shielded housing.
2. Brief Description of Related Developments
A great deal of attention is given, by both users and standards committees, to Electromagnetic Interference (EMI) performance of optoelectronic products, especially as the frequency at which signals are processed increases. Manufacturers of optoelectronic products invest a great deal of time and effort into ensuring that electromagnetic emissions from such products are kept to a minimum and that the optoelectronic products are also well-protected from external sources of EMI that might interfere with the operation of the optoelectronic products.
Although careful electrical design of both the assembly and individual electronic components, such as Integrated Circuits (ICs), of an optoelectronic product is important, shielding the electronic components from the outside world as efficiently as possible is usually the most effective known way to maximise the performance of the optoelectronic product. It is therefore known to contain the electronic components within a metallic housing, which can be grounded to form an efficient EMI shield.
In the case of optoelectronic modules, however, it is usually necessary to provide some form of optical interface, usually in the form of an optical connector, for example to form part of a pig-tail assembly, to couple an end of an optical fibre to a port of the optoelectronic module.
In order for tolerances, required for good optical connections between the optical fibre and the optoelectronic module, to be met, it is common for so-called “connector assemblies” to be based around non-metallic materials, such as ceramics or precision moulded plastics. In order to further ensure good optical coupling, light entering or leaving the optical fibre typically propagates through a lens provided as part of the port of the optoelectronic module.
However, whilst a majority of the housing for the optoelectronic module is usually metallic, the ceramic components and the lens provide a large aperture through which any electromagnetic radiation emitted by the active devices contained within the optoelectronic module, can escape. Emissions from the port and the connector assembly are often the greatest source of radiated EMI from this type of optoelectronic of module. As mentioned above, as the frequency at which signals are processed increases, electromagnetic emissions through the port and the connector assembly can increase.